liztemp <- function(Time, State, Pars)
{
  with(as.list(c(State, Pars)),
  {
    #Tdiff <- Tf-Ti
    
    DT <- -k*(Tb-(Ti+(Tf-Ti)*t))
    #DT <- -k*(Tb-Te)
    #DT = -k*(Tb-(Ti+(Tf-Ti)*t))
    
    return (list(DT))
  })
}                                  


Pars <- c(k = 0.6, Ti = 28, Tf = 35, t=1)
#Pars <- c(k = 0.6, Te = 35)
yini <- c(Tb = 29)
times=seq(0, 10, by=1)

out <- ode(func = liztemp, y=yini, parms = Pars, times = times)